WASHINGTON — ObamaCare’s regulations will lead millions of workers to cut back their hours, according to a nonpartisan congressional estimate that rankled the White House.

By 2021, the equivalent of 2.3 million full-time workers will be lost because of the law, the Congressional Budget Office estimated Tuesday.

The agency said health- care subsidies — which phase out as salaries go up — and government-provided health care through Medicaid for the lowest earners provide incentives for workers to put in fewer hours or leave the work force entirely.

It’s a loss that is “substantially larger” than an earlier estimate putting the loss at the equivalent of 800,000 jobs.

“Given the greater subsidies for health insurance to people with lower earnings and the higher taxes on some people under the [Affordable Care Act], some people will choose to work fewer hours,” according to the CBO.

As workers with higher incomes get pushed into higher brackets, it will “reduce their incentive to work [over the next 10 years],” according to the CBO analysis.

Nevertheless, the CBO acknowledged there was “substantial uncertainty” to its own numbers.